In an abusive realationship?

i have a friend, that is in an abusive realationship, she swears she needs him! he has complete mind control over her, he has her living in a dumpster(trashy trashy apartment, where the crack heads roam) they got into so many fights, and sense it was his apartment the police told her not to come over there again, if she does, she will go to jail. tell me why is she over there at this very moment? her mom has a serious disease and doctors says she will have a year to live and she has her mom stressing over her! what to do?